Blow molding is a well known method for producing fuel tanks In a typical fuel tank blow molding process, a generally cylindrical parison is extruded according to a size and an amount of material sufficient to create a fuel tank. The parison is placed into an open mold, a blow pin is extended up into an open end of the parison, and the mold closes. Portions of the parison are pinched between halves of the mold as the mold is closed, and pressurized gas is introduced into the interior of the parison through the blow pin to outwardly expand the parison into conformity with the shape of the mold cavity. After blowing, the blow pin is retracted and the molded tank is removed from the mold.
Downstream operations are then performed. For example, the molded tank is cooled at a cooling station, flashing is removed from the cooled tank at a trimming station, a hole is plugged in the tank where the blow pin was received, and openings are cut into the walls of the tank. For example, an opening may be cut into an upper wall of the tank to accommodate insertion of a fuel pump module and connection with a mounting flange of the module.